Timed vs. Time-triggered automata

To establish a semantic foundation for the synthesis of executable programs from timed models, we study in what sense the timed language (i.e. sequences of events with real-valued time-stamps) of a timed automaton is recognized by a digital machine. Based on the noninstant observability of events, we propose an alternative semantics for timed automata. We show that the new semantics gives rise to a natural notion of digitalization for timed languages. As a model for digital machines we use time-triggered automata - a subclass of timed automata with simplified syntax accepting digitalized timed languages. A time-triggered automaton is essentially a time table for a digital machine (or a digital controller), describing what the machine should do at a given time point, and it can be easily transformed to an executable program. Finally, we present a method to check whether a time-triggered automaton recognizes the language of a timed automaton according to the new semantics.